Retina

Kallman A, Capowski EE, Wang J, Kaushik AM, Jansen AD, Edwards KL, Chen L, Berlinicke CA, Joseph Phillips M, Pierce EA, Qian J, Wang T-H, Gamm DM, Zack DJ. Investigating cone photoreceptor development using patient-derived NRL null retinal organoids. Commun Biol 2020;3(1):82.Abstract
Photoreceptor loss is a leading cause of blindness, but mechanisms underlying photoreceptor degeneration are not well understood. Treatment strategies would benefit from improved understanding of gene-expression patterns directing photoreceptor development, as many genes are implicated in both development and degeneration. Neural retina leucine zipper (NRL) is critical for rod photoreceptor genesis and degeneration, with NRL mutations known to cause enhanced S-cone syndrome and retinitis pigmentosa. While murine Nrl loss has been characterized, studies of human NRL can identify important insights for human retinal development and disease. We utilized iPSC organoid models of retinal development to molecularly define developmental alterations in a human model of NRL loss. Consistent with the function of NRL in rod fate specification, human retinal organoids lacking NRL develop S-opsin dominant photoreceptor populations. We report generation of two distinct S-opsin expressing populations in NRL null retinal organoids and identify MEF2C as a candidate regulator of cone development.
Prahst C, Ashrafzadeh P, Mead T, Figueiredo A, Chang K, Richardson D, Venkaraman L, Richards M, Russo AM, Harrington K, Ouarné M, Pena A, Chen DF, Claesson-Welsh L, Cho K-S, Franco CA, Bentley K. Mouse retinal cell behaviour in space and time using light sheet fluorescence microscopy. Elife 2020;9Abstract
As the general population ages, more people are affected by eye diseases, such as retinopathies. It is therefore critical to improve imaging of eye disease mouse models. Here, we demonstrate that 1) rapid, quantitative 3D and 4D (time lapse) imaging of cellular and subcellular processes in the mouse eye is feasible, with and without tissue clearing, using light-sheet fluorescent microscopy (LSFM); 2) flat-mounting retinas for confocal microscopy significantly distorts tissue morphology, confirmed by quantitative correlative LSFM-Confocal imaging of vessels; 3) LSFM readily reveals new features of even well-studied eye disease mouse models, such as the oxygen-induced retinopathy (OIR) model, including a previously unappreciated 'knotted' morphology to pathological vascular tufts, abnormal cell motility and altered filopodia dynamics when live-imaged. We conclude that quantitative 3D/4D LSFM imaging and analysis has the potential to advance our understanding of the eye, in particular pathological, neuro-vascular, degenerative processes.
Liu C-H, Huang S, Britton WR, Chen J. MicroRNAs in Vascular Eye Diseases. Int J Mol Sci 2020;21(2)Abstract
Since the discovery of the first microRNA (miRNA) decades ago, studies of miRNA biology have expanded in many biomedical research fields, including eye research. The critical roles of miRNAs in normal development and diseases have made miRNAs useful biomarkers or molecular targets for potential therapeutics. In the eye, ocular neovascularization (NV) is a leading cause of blindness in multiple vascular eye diseases. Current anti-angiogenic therapies, such as anti-vascular endothelial growth factor (VEGF) treatment, have their limitations, indicating the need for investigating new targets. Recent studies established the roles of various miRNAs in the regulation of pathological ocular NV, suggesting miRNAs as both biomarkers and therapeutic targets in vascular eye diseases. This review summarizes the biogenesis of miRNAs, and their functions in the normal development and diseases of the eye, with a focus on clinical and experimental retinopathies in both human and animal models. Discovery of novel targets involving miRNAs in vascular eye diseases will provide insights for developing new treatments to counter ocular NV.
Xin T, Han H, Wu W, Huang X, Cui J, Matsubara JA, Song J, Wang F, Colyer M, Lei H. Idelalisib inhibits vitreous-induced Akt activation and proliferation of retinal pigment epithelial cells from epiretinal membranes. Exp Eye Res 2020;190:107884.Abstract
Proliferative vitreoretinopathy (PVR) is a blinding fibrotic eye disease that develops in 8-10% of patients who undergo primary retinal detachment-reparative surgery and in 40-60% of patients with open-globe injury. At present, there is no pharmacological treatment for this devastating disease. Vitreal growth factors activate their respective receptors of cells in the vitreous, trigger their downstream signaling transduction (e.g. phosphoinositide 3 kinases (PI3Ks)/Akt), and drive cellular responses intrinsic to the pathogenesis of PVR. PI3Ks play a central role in experimental PVR. However, which isoform(s) are involved in PVR pathogenesis remain unknown. Herein, we show that p110δ, a catalytic subunit of receptor-regulated PI3K isoform δ, is highly expressed in epiretinal membranes from patients with PVR, and that idelalisib, a specific inhibitor of PI3Kδ, effectively inhibits vitreous-induced Akt activation, proliferation, migration and contraction of retinal pigment epithelial cells derived from an epiretinal membrane of a PVR patient. Small molecules of kinase inhibitors have shown great promise as a class of therapeutics for a variety of human diseases. The data herein suggest that idelalisib is a promising PVR prophylactic.
Lee J-J, Ishihara K, Notomi S, Efstathiou NE, Ueta T, Maidana D, Chen XH, Iesato Y, Caligiana A, Vavvas DG. Lysosome-associated membrane protein-2 deficiency increases the risk of reactive oxygen species-induced ferroptosis in retinal pigment epithelial cells. Biochem Biophys Res Commun 2020;521(2):414-419.Abstract
Lysosome-associated membrane protein-2 (LAMP2), is a highly glycosylated lysosomal membrane protein involved in chaperone mediated autophagy. Mutations of LAMP2 cause the classic triad of myopathy, cardiomyopathy and encephalopathy of Danon disease (DD). Additionally, retinopathy has also been observed in young DD patients, leading to vision loss. Emerging evidence show LAMP2-deficiency to be involved in oxidative stress (ROS) but the mechanism remains obscure. In the present study, we found that tert-butyl hydroperoxide or antimycin A induced more cell death in LAMP2 knockdown (LAMP2-KD) than in control ARPE-19 cells. Mechanistically, LAMP2-KD reduced the concentration of cytosolic cysteine, resulting in low glutathione (GSH), inferior antioxidant capability and mitochondrial lipid peroxidation. ROS induced RPE cell death through ferroptosis. Inhibition of glutathione peroxidase 4 (GPx4) increased lethality in LAMP2-KD cells compared to controls. Cysteine and glutamine supplementation restored GSH and prevented ROS-induced cell death of LAMP2-KD RPE cells.
Shakhmantsir I, Dooley SJ, Kishore S, Chen D, Pierce E, Bennett J, Sehgal A. RNA Splicing Factor Mutations That Cause Retinitis Pigmentosa Result in Circadian Dysregulation. J Biol Rhythms 2020;35(1):72-83.Abstract
Circadian clocks regulate multiple physiological processes in the eye, but their requirement for retinal health remains unclear. We previously showed that Drosophila homologs of spliceosome proteins implicated in human retinitis pigmentosa (RP), the most common genetically inherited cause of blindness, have a role in the brain circadian clock. In this study, we report circadian phenotypes in murine models of RP. We found that mice carrying a homozygous H2309P mutation in () display a lengthened period of the circadian wheel-running activity rhythm. We show also that the daily cycling of circadian gene expression is dampened in the retina of H2309P mice. Surprisingly, molecular rhythms are intact in the eye cup, which includes the retinal pigment epithelium (RPE), even though the RPE is thought to be the primary tissue affected in this form of RP. Downregulation of , another RNA splicing factor implicated in RP, leads to period lengthening in a human cell culture model. The period of circadian bioluminescence in primary fibroblasts of human RP patients is not significantly altered. Together, these studies link a prominent retinal disorder to circadian deficits, which could contribute to disease pathology.
Zantut PRA, Veras MM, Yariwake VY, Takahashi WY, Saldiva PH, Young LH, Damico FM, Fajersztajn L. Effects of cannabis and its components on the retina: a systematic review. Cutan Ocul Toxicol 2020;39(1):1-9.Abstract
Cannabis is the most prevalent drug in the world and its consumption is growing. Cannabinoid receptors are present in the human central nervous system. Recent studies show evidence of the effects of cannabinoids on the retina, and synthesising the results of these studies may be relevant for ophthalmologists. Thus, this review adopts standardised, systematic review methodology to investigate the effects of exposure to cannabis and components on the retina. We searched five online databases for the combined terms for outcome ("retina") and exposure ("cannabis"). Eligibility of studies were conducted by two independent reviewers, and risk of bias was assessed. We retrieved 495 studies, screened 229 studies, assessed 52 studies for eligibility, and included 16 studies for qualitative analysis. The cannabinoids most frequently investigated were delta-9-tetrahydrocannabinol (THC), abnormal cannabidiol, synthetic cannabinoid, and cannabidiol (CDB). The outcomes most studied were neuroretinal dysfunction, followed by vascular effects. The studies also included investigation of neuroprotective and anti-inflammatory effects and teratogenic effects. This review suggests that cannabinoids may have an important role in retinal processing and function.
Rao P, Lertjirachai I, Yonekawa Y, Hasbrook M, Thomas BJ, Wood EH, Mehta N, Mane G, Drenser KA, Trese MT, Capone A. ETIOLOGY AND CLINICAL CHARACTERISTICS OF MACULAR EDEMA IN PATIENTS WITH FAMILIAL EXUDATIVE VITREORETINOPATHY. Retina 2020;40(7):1367-1373.Abstract
PURPOSE: To describe the etiology and clinical characteristics of macular edema (ME) in patients with familial exudative vitreoretinopathy. METHODS: Observational, retrospective case series of 30 patients (34 eyes) with ME and familial exudative vitreoretinopathy who underwent spectral-domain optical coherence tomography imaging between 2009 and 2016. Baseline and follow-up optical coherence tomographies were correlated with color fundus photography and fluorescein angiography. RESULTS: The average age was 20.6 years (6.6-68.7). Eighteen eyes exhibited cystoid ME (52.9%), 14 noncystoid ME (41.2%), and 2 eyes (5.9%) with both. Macular edema was foveal in 52.9% (n = 18). Eighteen of 24 eyes (64.3%) with an available fluorescein angiography showed leakage from ME. The most common structural feature was posterior hyaloidal organization/contraction (n = 15). Sixteen eyes were treated with topical or intravitreal steroids (n = 6), intravitreal anti-vascular endothelial growth factor (n = 3), or pars plana vitrectomy with membrane stripping (n = 7). There was no difference between mean preoperative and postoperative LogMAR visual acuity (0.63 [20/85] vs. 0.87 [20/148], P = 0.35) after vitrectomy despite a statistical improvement in the mean central foveal thickness (596 mm vs. 303 mm, P = 0.04). CONCLUSION: Macular edema in familial exudative vitreoretinopathy occurs most commonly because of traction. Vitrectomy is effective for relieving tractional forces with anatomical improvement.
Lally DR, Kasetty MA. CLOSURE OF SMALL MACULAR HOLES USING VITRECTOMY SURGERY WITH INTERNAL LIMITING MEMBRANE PEELING WITHOUT THE USE OF INTRAOCULAR GAS TAMPONADE: BROADENING THE UNDERSTANDING OF THE MACULAR HOLE PATHOPHYSIOLOGY. Retin Cases Brief Rep 2020;14(2):104-109.Abstract
PURPOSE: To determine whether small macular hole closure can be achieved with 25-G vitrectomy surgery with internal limiting membrane peeling without the use of intraocular gas tamponade or facedown positioning. METHODS: 25-G vitrectomy surgery with internal limiting membrane peeling without the use of intraocular gas tamponade or positioning was performed on 20 eyes with a small (<400-µm diameter), full-thickness macular hole. RESULTS: In 17 of 20 eyes (85%), the hole had closed. Three holes had closed by Postoperative Day 1, 13 holes by Postoperative Week 1, 16 holes by Postoperative Week 2, and 17 holes by Postoperative Week 6. At Postoperative Month 1, vision improved in 16 of 17 eyes in which the macular hole had closed. One hole that had not closed at the first postoperative week and two holes that had not closed at the third postoperative week required follow-up surgery with intraocular gas tamponade and facedown positioning, after which the hole closed. The mean preoperative visual acuity was 0.626 logMAR (20/85), and the mean postoperative visual acuity after 1 month was 0.392 logMAR (20/50) (P < 0.001). CONCLUSION: Vitrectomy surgery with internal limiting membrane peeling without the use of gas tamponade or positioning can achieve closure of small macular holes.
Sakurada Y, Fragiotta S, Leong BCS, Parikh R, Hussnain AS, Freund BK. RELATIONSHIP BETWEEN CHOROIDAL VASCULAR HYPERPERMEABILITY, CHORIOCAPILLARIS FLOW DENSITY, AND CHOROIDAL THICKNESS IN EYES WITH PACHYCHOROID PIGMENT EPITHELIOPATHY. Retina 2020;40(4):657-662.Abstract
PURPOSE: To use swept-source optical coherence tomography and swept-source optical coherence tomography angiography to investigate potential relationships between choroidal vascular hyperpermeability (CVH) seen with indocyanine green angiography (ICGA), choriocapillaris flow density, and choroidal thickness in eyes with pachychoroid pigment epitheliopathy. METHODS: Patients with pachychoroid pigment epitheliopathy were prospectively imaged with 12-mm × 12-mm swept-source optical coherence tomography, 12-mm × 12-mm swept-source optical coherence tomography angiographyA, and ICGA. Binarized choriocapillaris OCTA images were superimposed with ICGA images in which CVH area had been isolated. Choriocapillaris flow density within or outside the quadrants of CVH was calculated and the ratio of these two values was determined. The presence of CVH and choroidal thickness was evaluated at 9 locations within a central 3-mm × 3-mm area to explore the relationship between these 2 factors. RESULTS: Ten eyes from 10 patients were enrolled in the present study. Choriocapillaris flow density within quadrants of CVH area was significantly lower compared with quadrants without CVH (P < 0.001). The mean choriocapillaris flow density ratio was 0.86 ± 0.10 (range: 0.65-0.99). From among the 90 locations in 10 study eyes, 48 were within areas of CVH. Choroidal thickness was greater in quadrants of CVH compared with areas without CVH (P < 0.001, 455 ± 122 µm vs. 297 ± 93 µm). CONCLUSION: Reduced choriocapillaris flow density, increased choroidal thickness, and CVH appear to co-localize in eyes with pachychoroid pigment epitheliopathy.
Lizano P, Bannai D, Lutz O, Kim LA, Miller J, Keshavan M. A Meta-analysis of Retinal Cytoarchitectural Abnormalities in Schizophrenia and Bipolar Disorder. Schizophr Bull 2020;46(1):43-53.Abstract
BACKGROUND: Schizophrenia (SZ) and bipolar disorder (BD) are characterized by reductions in gray matter and white matter. Limitations in brain imaging have led researchers to use optical coherence tomography (OCT) to explore retinal imaging biomarkers of brain pathology. We examine the retinal layers that may be associated with SZ or BD. METHODS: Articles identified using PubMed, Web of Science, Cochrane Database. Twelve studies met inclusion for acutely/chronically ill patients. We used fixed or random effects meta-analysis for probands (SZ and BD), SZ or BD eyes vs healthy control (HC) eyes. We adjusted for sources of bias, cross-validated results, and report standardized mean differences (SMD). Statistical analysis performed using meta package in R. RESULTS: Data from 820 proband eyes (SZ = 541, BD = 279) and 904 HC eyes were suitable for meta-analysis. The peripapillary retinal nerve fiber layer (RNFL) showed significant thinning in SZ and BD eyes compared to HC eyes (n = 12, SMD = -0.74, -0.51, -1.06, respectively). RNFL thinning was greatest in the nasal, temporal, and superior regions. The combined peripapillary ganglion cell layer and inner plexiform layer (GCL-IPL) showed significant thinning in SZ and BD eyes compared to HC eyes (n = 4, SMD = -0.39, -0.44, -0.28, respectively). No statistically significant differences were identified in other retinal or choroidal regions. Clinical variables were unrelated to the RNFL or GCL-IPL thickness by meta-regression. CONCLUSION: The observed retinal layer thinning is consistent with the classic gray- and white-matter atrophy observed on neuroimaging in SZ and BD patients. OCT may be a useful biomarker tool in studying the neurobiology of psychosis.
Bagheri S, Pantrangi M, Sodhi SK, Bagheri S, Oellers P, Scholl HPN. A NOVEL LARGE HOMOZYGOUS DELETION IN THE CELLULAR RETINALDEHYDE-BINDING PROTEIN GENE (RLBP1) IN A PATIENT WITH RETINITIS PUNCTATA ALBESCENS. Retin Cases Brief Rep 2020;14(1):85-89.Abstract
PURPOSE: To report the phenotypic and genotypic data of a patient with retinitis punctata albescens carrying a novel deletion in the RLBP1 gene. RESULTS: A woman of Iranian descent in her forties with a history of progressive visual deterioration since early childhood exhibited phenotypic features of retinitis punctata albescens with multiple white dots in the posterior pole and macular atrophy in both eyes. The microarray analysis identified a ∼2.160 kb homozygous deletion corresponding to a minimum deletion boundary of chr15q26.1:89,756,882-89,759,041/GRCh37 (hg19), which encompasses exon 6 of the RLBP1 gene. CONCLUSION: We describe a novel large homozygous deletion in the RLBP1 gene encoding the cellular retinaldehyde-binding protein in a patient of Iranian descent with retinitis punctata albescens. Genotype-phenotype studies may provide more information about the functions of the RLBP1 encoding proteins and the disease course, because RLBP1 mutations are associated with high phenotypic variability and are therefore a necessity for future tailored individual therapies.
Brydon EM, Bronstein R, Buskin A, Lako M, Pierce EA, Fernandez-Godino R. AAV-Mediated Gene Augmentation Therapy Restores Critical Functions in Mutant PRPF31 iPSC-Derived RPE Cells. Mol Ther Methods Clin Dev 2019;15:392-402.Abstract
Retinitis pigmentosa (RP) is the most common form of inherited vision loss and is characterized by degeneration of retinal photoreceptor cells and the retinal pigment epithelium (RPE). Mutations in pre-mRNA processing factor 31 () cause dominant RP via haploinsufficiency with incomplete penetrance. There is good evidence that the diverse severity of this disease is a result of differing levels of expression of the wild-type allele among patients. Thus, we hypothesize that -related RP will be amenable to treatment by adeno-associated virus (AAV)-mediated gene augmentation therapy. To test this hypothesis, we used induced pluripotent stem cells (iPSCs) with mutations in and differentiated them into RPE cells. The mutant iPSC-RPE cells recapitulate the cellular phenotype associated with the PRPF31 pathology, including defective cell structure, diminished phagocytic function, defects in ciliogenesis, and compromised barrier function. Treatment of the mutant iPSC-RPE cells with AAV- restored normal phagocytosis and cilia formation, and it partially restored structure and barrier function. These results suggest that AAV-based gene therapy targeting RPE cells holds therapeutic promise for patients with -related RP.
Reshef ER, Habib LA, Rao R, Modjtahedi BS, Eliott D, Freitag SK, Reinshagen KL, Lee NG. Clinical and radiographic features of hydrolyzed MIRAgel scleral buckles: A comparative analysis. Clin Imaging 2019;60(1):10-15.Abstract
The MIRAgel (hydrogel) scleral buckle, introduced in the 1980s, was a novel material to repair retinal detachments. It was later discontinued due to the frequency of long-term complications related to buckle hydrolysis and expansion. These complications included pain, limited extraocular motility, and more serious complications such as infection or scleral perforation, which ultimately necessitated surgical extraction as late as 20-30 years after placement. Prompt and proper diagnosis and treatment is often delayed as these buckle-associated complications frequently mimic other orbital pathologies such as tumors or infections. The hydrolyzed MIRAgel buckle exhibits distinct radiographic features that are helpful in arriving at the correct diagnosis, particularly in cases of ambiguous clinical presentation or history. Here, we expand on the previously described radiographic features of hydrolyzed MIRAgel and compare them to features of common, mimicking orbital pathology.

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